Comparison of Three Irrigation Regimes and Their Effect On Dollar Spot Disease of Creeping Bentgrass.

One of the most economically important diseases of golf course turf is dollar spot, caused by Sclerotinia homoeocarpa.  Integrated management practices and alternatives to fungicides are being investigated to combat turfgrass diseases, including dollar spot.  This study compares three different irrigation regimes, based on frequency and timing, while integrating the use of resistant cultivars to assess disease management. Three irrigation regimes were randomly assigned to three replicate 11 m x 11 m irrigation plots. Irrigation regimes included: light (approximately 0.25 cm) daily at 5:00 am, light (approximately 0.25 cm) daily at 10:00 pm, or infrequent (1-2 times weekly to equal the total amount of irrigation applied to the daily treatments) at 10:00 pm.  Within each irrigation plot, three creeping bentgrass cultivars were randomized in four replicate complete blocks in split-plots measuring 2.7 m x 3.7 m.  Preliminary results from one year of field testing indicate that light irrigation applied at 10:00 pm on a daily basis resulted in lower relative area under disease progress curve (AUDPC) for dollar spot in three creeping bentgrass cultivars than the same approximate total weekly volume of irrigation applied on an infrequent basis (1-2 times weekly) at 10 pm at night.